Intrusive Related Gold Deposits

October

2005

Issue 87

Classifying, Distinguishing and Exploring for Intrusion-Related Gold Systems

Craig J.R. Hart Yukon Geological Survey P.O. Box 2703 (K-102)

Whitehorse, Yukon, Y1A 2C6 Canada E-mail: [email protected]

Introduction

Intrusion-related gold systems (IRGS) are a newly-defined (1999) deposit classi-fication (based mainly on well-studied deposits in Alaska and Yukon) that is al-ready mired in confusion, nomenclature uncertainty and misapplication. Increas-ingly, gold deposits are mis-assigned an IRGS classification because: 1) the no-menclature of intrusion-related gold mod-els has been rapidly evolving; 2) the char-acteristics of the classification are broadly defined to include a wide range of deposit types that overlap with other gold deposit types; and 3) granitoid intrusions are com-mon features of orogenic belts and are an obvious fluid source for any proximal gold occurrence.

Ambiguous, poorly understood or poorly-defined deposit model classifica-tions are an economic geologist’s greatest weakness as they result in ineffective exploration strategies. Deposit classifica-tions can be better differentiated from others by using a set of distinguishing features and not characteristics that may be common to many hydrothermal deposit types. Herein, the historical evolution of intrusion-related gold deposit concepts is briefly presented, followed by a statement of the current state of intrusion-related gold models, and concluded with a set of characteristics by which IRGS can be

distinguished from other gold deposit types in similar geological settings.

Evolution of Intrusion-Related Gold Classifications

Intrusion-related gold classifications imply a genetic connection between gold ores and granitic plutons. These associa-tions rocks have been long recognized (e.g., Agricola, 1556; DeLaunay, 1900; Lindgren, 1933, Spurr, 1923; Niggli, 1929; Emmons, 1926, 1933), but the contempo-rary geological literature prior to 1990 was essentially devoid of intrusion-related gold models. For example, there is no mention of such milestone contributions on mineral deposit types in models such as the 75th Anniversary Volume of Economic Geology (Skinner, 1981), the U.S. Geological Sur-vey’s Ore Deposit Models (Cox & Singer, 1986), GAC Ore Deposit Models volumes (Roberts and Sheahan, 1988, 1994) or the British Columbia Geological Survey’s original Mineral Deposit Profiles (http://

www.em.gov.bc.ca/mining/GeolSurv/MetallicMinerals/MineralDepositProfiles/default.htm). The lack of progress re-sulted, in part, from the dearth of gold deposit research prior to its price increase in 1980. There were of course gold-rich skarn deposits, which, by their very nature are intrusion-related, and of course, gold was recognized at Bingham porphyry since mining started in 1906, but Sillitoe (1979) was among the first to emphasize a gold-rich porphyry classification.

Early intrusion-related gold classifica-tions were based on a porphyry copper classification. Gold-rich and gold-only porphyry copper systems had been long recognized and were identified and docu-mented by Sillitoe (1979, 1995). Sillitoe (1995) recognized that they represented gold-rich end members and were not a new classification. The “porphyry” no-menclature was exported to refer to intru-sion-hosted, low-grade, gold-only deposits at Fort Knox (Hollister, 1992; Bakke,

(Continued on page 4)

Inside this issue: 2006 Derry & Gross Winners 10

Editorial - D. Duff 12 Book Review - Inco comes to Labrador 17

Calendar of Events 18

Figure 1. Broad distribution of the Tintina Gold Province (TGP) across Alaska and Yukon show-ing individual gold deposits (stars) and notable occurrences mentioned in the text that are consid-ered to be of intrusion-related origin. However, many deposits are not intrusion-related or are at least controversial. The TGP is composed of numerous different gold districts with varying forms and ages of mineralization.

200520052005---2006 GAC MINERAL DEPOSITS 2006 GAC MINERAL DEPOSITS 2006 GAC MINERAL DEPOSITS DIVISION DIRECTORSDIVISION DIRECTORSDIVISION DIRECTORS

Chairperson: Jan Peter Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8; Tel: (613) 992-2376; Fax: (613) 996-3726 Email: [email protected] Past Chairperson: Hendrik Falck C.S. Lord Northern Geoscience Centre, Box 1500, 4601-B, 52 Avenue, Yellowknife, NT X1A 2R3; Tel: (867) 669-2636; Fax: (867) 669-2725 Email: [email protected]

Vice Chairperson: Suzanne Paradis Natural Resources Canada, 9860 West Saanich Road, Room 4718, Sidney, BC V8L 4B2; Tel: (250) 363-6732; Fax: (250) 363-6565 Email: [email protected]

Secretary: ‘Lyn Anglin Geoscience BC, 410-890 W. Pender St., Vancouver, BC V6C 1J9; Tel: (604) 662-4147; Fax: (604) 662-4107 Email: [email protected]

Treasurer: Jason Dunning Expatriate Resources, Suite 475, 701 Howe Street, Vancou-ver, BC V6C 2B3; Tel: (604) 682-5474, ext. 225; Fax (604) 682-5404 Email: [email protected] Publications: Dirk Tempelman-Kluit Tempelman-Kluit Consulting, 4697 West 4th Avenue, Vancou-ver, BC V6R 1R6; Tel: (604) 224-5582; Fax: (604) 224-6903 Email: [email protected]

Professional Development–Field Trips: Dani Alldrick BC Geological Survey, 5 - 1810 Blanshard Street, Victoria, BC V8T 4J1; Tel: (250) 952-0412; Fax: (250) 952-0381 Email: [email protected]

Short Course Coordinator: Steve Piercey Mineral Exploration Research Centre, Dept. of Earth Sciences, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6; Tel: (705) 675-1151 ext. 2364; Fax: (705) 675-4898 Email: [email protected]

Medals Committee and Website Manager: Dan Marshall Dept. of Earth Sciences, Simon Fraser University, Vancouver, BC; Tel: (604) 291-5474; Fax: (604) 291-4198 Email: [email protected]

200520052005---2006 GAC MINERAL DEPOSITS 2006 GAC MINERAL DEPOSITS 2006 GAC MINERAL DEPOSITS DIVISION EXECUTIVE LISTDIVISION EXECUTIVE LISTDIVISION EXECUTIVE LIST

2 October 2005– Gangue No. 87

• Ross Sherlock (2003-2006) ESS/GSC-MRGB/CNGO, Natural Resources Canada, 626 Tumiit Building, P.O. Box 2319, Iqaluit, NU; Tel: (867) 979-3539; Fax: (867) 979-0708 Email: [email protected]

• Steve McCutcheon (2003-2006) New Brunswick Department of Natural Resources, P.O. Box 50, 495 Riverside Drive, Bathurst, NB; Tel: (506) 547-2070; Fax (506) 547-7694 Email: [email protected]

• Gema Olivo (2003-2006) Geological Sciences, Queens University, Kingston, ON; Tel: (613) 533-6998; Fax: (613) 533-6592 Email: [email protected]

• Bob Cathro (2004-2007) Cathro Exploration Corporation, 3230 Dogwood Road, RR #1 Chemainus, BC, V0R 1K2; Tel: (250) 246-4738; Fax: (250) 246-4738 Email: [email protected]

• Steve Rowins (2003-2006) Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC; Tel: (604) 822-9561; Fax: (604) 822-6088 Email: [email protected]

• Rebecca Sproule (2004-2007) Department of Earth Sciences, Laurentian University, Sudbury, ON, P3E 2C6; Tel: (705) 675-1151, ext. 1325; Fax: (705) 675-4898 Email: [email protected]

• Craig Hart (2004-2007) Yukon Geological Survey, Box 2703 (K-10), Whitehorse, YK, X1A 2C6; Tel: (867) 667-8508; Fax: (867) 393-6232 Email: [email protected] • Robert Carpenter (2005-2008) Committee Bay Resources, 625 Howe St., Suite 1440, Vancouver, BC, V6T 2T6; Tel: (604) 220-0164 Email: [email protected]

• Moira Smith (2005-2008) TECK COMINCO Limited, #600 - 200 Burrard Street, Vancouver, BC V6C 3L9; Tel: (604) 640-5373; Fax: (604) 685-3069 Email: [email protected]


President: Damien Duff Ontario Ministry of Northern Development and Mines Willett Green Miller Centre, 933 Ramsey Lake Road Sudbury, ON, P3E 6B5; Tel: (705) 670-5876; Fax: (705) 670-581 Email: [email protected] Past President: Reg Olson Alberta Geological Survey, 4th Floor, Twin Atria 4999-98 Ave-nue, Edmonton, AB, T6B 2X3; Tel: (780) 427-1741; Fax: (780) 422-1459 Email: [email protected]

Vice President: Steve McRoberts Teck-Cominco Ltd., PO Box 938, Stn. Main, Kamloops, BC, V2C 5N4; Tel: (250) 372-0032; Fax: (250) 372-1285 Email: [email protected]

Vice President Elect: Chris Davis Inco Technical Services Ltd., P.O. Box 1516, Capreol, ON, P0M 1H0; Tel: (705) 858-0386 Email: [email protected]

Secretary/Treasurer: Laurie Gaborit High River Gold Mines Ltd., Suite 1700, 155 University Ave-nue, Toronto, ON, M5H 3B7; Tel: (416) 947-1440; Fax: (416) 360-0010 Email: [email protected] Publications: David Sinclair Geological Survey of Canada, 601 Booth Street, 6th Floor, Room 675, Ottawa, ON, K1A 0E8; Tel: (613) 992-9810; Fax: (613) 996-3726 Email: [email protected]

Field Conference Coordinator: Position Vacant

200520052005---2006 CIM GEOLOGICAL 2006 CIM GEOLOGICAL 2006 CIM GEOLOGICAL SOCIETY EXECUTIVE LISTSOCIETY EXECUTIVE LISTSOCIETY EXECUTIVE LIST

• Reg Olson (Awards) Alberta Geological Survey, 4th Floor, Twin Atria 4999-98 Ave-nue, Edmonton, AB, T6B 2X3; Tel: (780) 427-1741; Fax (780) 422-1459 Email: [email protected]

• George O’Reilly (Bulletin Associate Editor) Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, NS, B3J 2T9; Tel: (902) 424-2517; Fax: (902) 424-0527 Email: [email protected]

• Jeremy Richards (EMG Editor) Department of Earth and Atmospheric Sciences, University of Alberta, Earth Sciences Building Room 3-02, Edmonton, AB, T6G 2E3; Tel: (780) 492-3430; Fax: (780) 492-2030 Email: [email protected]

• Andrew Conly (Mineral Deposits Re-search/University Visiting Lecturer)

Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1; Tel: (807) 343-8463; Fax: (807) 346-7853 Email: [email protected]

• Tom Schroeter (Special Volumes Editor) British Columbia Geological Survey, Vancouver Mineral Devel-opment Office, Mining and Minerals Division, Suite 300-865 Hornby Street, Vancouver, BC, V6Z 2G3; Tel: (604) 660-2812 Email: Tom. [email protected]

• David Lentz (Public Affairs/Education) University of New Brunswick, Department of Geology, PO Box 4400, Fredericton, NB, E3B 5A3; Tel: (506) 453-4804; Fax: (506) 453-5055 Email: [email protected]

• Frank Santaguida (Liaison) Falconbridge, Exploration Office, Kidd Creek Minesite, PO Box 1140, Timmins, ON, P4N 7B5; Tel: (705) 264-5200, ext. 8231; Fax: (705) 267-8874 Email: [email protected]

• Phil Thurston (Sudbury Section Representative) Mineral Exploration Research Centre, Laurentian University, Sudbury, ON, P3E 2C6; Tel: (705) 675-1151, ext. 2372 Email: [email protected]

• Phil Olson (Saskatoon Section Representative) Claude Resources Inc., 214 Coben Cr., Saskatoon, SK, S7S 1B3; Tel: (306) 244-6916; Email: [email protected]

200520052005---2006 CIM GEOLOGICAL 2006 CIM GEOLOGICAL 2006 CIM GEOLOGICAL SOCIETY REPRESENTATIVESSOCIETY REPRESENTATIVESSOCIETY REPRESENTATIVES


1995) and Dublin Gulch (Hitchins and Ossrich, 1995). These examples however, lack numerous defining features of porphyry deposits, such as multidirectional stockworks, disseminations, hydrothermal breccias, and widespread and concentric alteration shells, but served to emphasize the differences in the physical and chemical processes involved in their formation compared to typical porphyry systems. Most of these distinctions result from their deeper level of intrusion compared to porphyry systems. Both Lang et al. (2000) and Rombach and Newberry (2001) recognized that shallower IRGS, such as Shotgun, had characteris-tics more similar to typical porphyry systems, and therefore emphasized the depth control on intrusion-related characteristics.

Sillitoe (1991) first established an intrusion-related classification by defining a “broad spectrum of gold mineralization styles” within epizonal environments. He showed clear evidence of deposit variability and interrelationships within an intrusion-related environment and identified six classes: porphyry, skarn, intrusion-hosted, carbonate-replacement, breccia and vein. Most exam-ples were associated with porphyry copper-style mineralization in magnetite-series (oxidized), I-type intrusions in circum-Pacific island arc settings. As such, these deposits largely represent an “oxidized” intrusion-related gold classification.

Newberry et al. (1995) introduced plutonic-hosted gold deposits emphasizing Bi and Te enrichments and correlations with “intrinsic” or genetically-associated gold deposits. Similarly, McCoy et al. (1997) used the term plutonic-related gold deposits to classify a wide range of gold deposit types from several districts through Alaska, and emphasized magmatic fluid evolution of, and differences from, porphyry systems. Their efforts assembled a broad array of characteristics into a single model over a range of depths. Wall and Taylor (1990) and Wall (1999) created a Thermal Aureole Gold model that emphasized proximity to plutons as favourable mineralizing sites due to structures, steep fluid, temperature and chemical gradients and other features. The model indicated numerous possible fluid sources for the deposits, but didn’t specifically imply a direct genetic association with the plu-ton.

An intrusion-related gold vein classification indicated by Sillitoe (1991) was further amplified by Sillitoe and Thompson (1998). The examples used are wide-ranging, and thought to reflect differences in magma chemistry and oxidation state. The broad variations in associated characteristics partly overlap those of orogenic gold veins (Groves et al., 1998) and further emphasize the need for distinguishing characteristics between these two classifications, as was discussed by Sillitoe and Thompson (1998) and Groves et al. (2003).

A new intrusion-related class introduced by Thompson et al. (1999) emphasized intrusion-related gold mineralization in regions lacking copper, but known for W and Sn deposits, and having an associated Bi-Te-As-Mo-Sb metal tenor. The deposits are asso-ciated with intrusions that are more felsic and more reduced than those highlighted by Sillitoe (1991, 1995) and are partly of S-type character. These systems are clearly distinct from intrusion-related gold deposits associated with chalcophile oxidized mag-mas. In order to differentiate between the two types, Lang et al. (2000) introduced the term intrusion-related gold “systems” (IRGS), and provided perhaps the clearest refinement of defining characteristics. “System” was emphasized to high-light the wide range of associated gold deposit styles within this scheme. The contribution by Thompson and Newberry (2000) further emphasized the difference between the two classifications by calling them “reduced” IRGS to emphasize the importance of the reduced oxidation state of the associated granitoids and exsolved fluids. Some examples of reduced IRGS granitoids may not be strongly reduced, but are significantly less oxidized than typical granitoids associated with porphyry occurrences.

Although gold is traditionally considered to be associated with oxidized intrusions and chalcophile enrichments (e.g., Ishihara, 1981), the reduced character of some gold-related intrusions had been previously recognized for Alaskan examples by Leveille et al. (1988) who also indicated an alkalic association, and by Keith and Swan (1987) for intrusion-related gold deposits in the south-western USA. A reduced intrusion-related mineral class was also recognized by Rowins (2000) who introduced “reduced por-phyry Cu-Au deposits”, using Fort Knox, Shotgun and Telfer as examples, emphasizing them as a base-metal depleted variation of the traditional porphyry theme. Robert (2001) reintroduced syenite-associated gold deposits as Archean examples, but these appear unrelated to other intrusion-related classifications.

The reduced IRGS model was mainly developed in response to observations, exploration, discoveries, and research on gold systems across central Alaska and Yukon where they are part of the Tintina Gold Province (TGP) (Figs. 1 & 2), and includes well-studied examples such as Fort Knox (Bakke, 1995), Dublin Gulch (Maloof et al., 2001), Clear Creek (Marsh et al., 2003), and Scheelite Dome (Mair, 2004). The association of the Tintina Gold Province with intrusion-related gold systems was crystallized by Tucker and Smith (2000) such that TGP gold deposits are broadly considered be entirely intrusion-related. This led Hart et al. (2002) to emphasize that TGP deposits comprise parts of numerous gold districts that formed at several times during the Meso-zoic in response to different geological events. They further emphasized that only some of the mineralization is unequivocally intrusion-related, and that many deposits are better characterized as epizonal or shear-hosted because they lack most intrusion-related characteristics and a causal pluton is not apparent. Hart et al. (2004a) further showed that the TGP is underlain by sev-eral different plutonic suites with different metallogenic expressions with the best intrusion-related gold systems (e.g., Fort Knox, Dublin Gulch) being related to the once continuous Fairbanks-Tombstone-Mayo plutonic suite.

Misclassified Deposits?

Despite the confusion, or perhaps because of it, this recently-developed intrusion-related gold classification is extremely ap-pealing and has been broadly adopted in exploration and research circles. It is the topic of special volumes (Tucker and Smith, 2000; Lang and Baker, 2001), and intrusion-related models have been called upon to describe the genesis of an increasing num-ber of gold deposits and districts throughout the world. The proliferation of the classification has resulted firstly because of the ease of associating a gold deposit with any proximal intrusion, but secondly because the classification is commonly confused and mixed with characteristics of the oxidized intrusion-related gold deposits classification of Sillitoe (1991). The resultant large range of intrusion-related characteristics span a wide range of hydrothermal mineralization characteristics and have resulted in

October 2005– Gangue No. 87 5

Table 1. Historical Development of Intrusion-related Nomenclature and concepts


Name Main Features Notable Examples Reference

Gold-rich porphyry copper deposits

• Recognized gold enrichments as part of porphyry spectrum

Bingham, Marte, Lepanto, Skouries

Sillitoe, 1993

Intrusion-related gold de-posits

• Wide variety of epizonal mineralization in the porphyry to epithermal transition

• Six types - skarn, porphyry, replacement, breccia, vein

• Chalcophile metal association

• Associated with oxidized, I-type intru-sions

Kidston, Boddington, Salave, Kori Kollo, Muruntau

Sillitoe, 1991

Gold porphyry • Included as porphyry due to the intrusion-hosted, bulk tonnage, low grade nature

Fort Knox, Dublin Gulch, Bakke, 1995; Hitchins and Orrsich, 1995; Schroeter, 1995

Thermal Aureole Gold • Proximity to plutons provides structurally favourable sites for mineralization due to thermal and chemical fluxes and multiple fluid sources

Fort Knox, Donlin Creek, Muruntau, Callie, Telfer, Suk-hoi Log, Kumtor

Wall and Taylor, 1990; Wall,1999

Plutonic hosted gold, intrin-sic

• Noted Bi and Te enrichments and corre-lations with intrusion-hosted gold deposits

Fort Knox, Ryan Lode, Circle, Vinasale

Newberry et al., 1995

Plutonic related gold • Emphasized fluid differences from por-phyry deposits

Fort Knox, Ryan Lode, Pogo, Cleary Hill, Nixon Fork, Shot-gun, True North, Donlin Creek

McCoy, 1997

Intrusion-related gold veins • Broad spectrum of characteristics reflect the nature of associated magma

Linglong, Ryan Lode, Dong-ping, Snip

Sillitoe and Thomp-son, 1998

Syenite-associated • Archean examples in greenstone belt

• Cu-rich sulphide disseminations

Malartic, Beattie, Holt-McDermott

Robert, 2001

Intrusion-related gold de-posits in Sn-W provinces

• Included a wide range of deposit styles

• Gold associated with lithophile metal signature

Fort Knox, Kidston, Timbarra, Kori Kollo, Mokrsko, Salave

Thompson et al., 1999

Tintina Gold Belt • Selected papers on a wide range of gold deposits in Alaska and Yukon included as intrusion-related

Fort Knox, Shotgun, Scheelite Dome, Longline, Pogo, Donlin Creek

Tucker and Smith, 2000

Intrusion-related gold sys-tems

• Emphasis on “Systems”, and differences from porphyry deposits

Fort Knox, Pogo, Brewery Creek, Mokrsko, Salave, Kidston, Timbarra, Vasilk-ovskoe

Lang et al., 2000

Reduced Cu-Au porphyry • Copper depleted Cu-Au porphyry Fort Knox, Shotgun Rowins, 2000

Reduced intrusion-related gold systems

• Reduced primary oxidation state of intru-sion

Fort Knox, Pogo, Donlin Creek, Dublin Gulch

Thompson and New-berry, 2000

Tintina Gold Province • Excluded gold districts and deposits from intrusion-related classification

• Divided Tintina Gold Province mineraliza-tion into intrusion-related, epizonal and shear hosted

Fort Knox, Dublin Gulch, Clear Creek, Scheelite Dome

Hart et al., 2002


numerous vein deposits being assigned an intrusion-related classification. For example, intrusion-related gold mineralization is interpreted within turbidite-hosted orogenic gold systems in the western Lachlan fold belt of Victoria (Miller and Wilson, 2004; Bierlein and McKnight, 2005), in New Zealand’s Otago region (de Ronde et al., 2000), and in the Meguma terrane of Nova Scotia (Kontak et al., 2004). Similarly, intrusion-related gold deposit models have been attributed to deposits in Archean orogenic gold camps including Wallaby (Hall et al., 2001), and some of the Golden Mile orebody (Walshe et al., 2005), both in the Yilgarn cra-ton. Other Phanerozoic examples of intrusion-hosted gold have been stated, such as vein deposits in China’s Shandong Pennin-sula (e.g., Linglong; Wang et al., 1998) and many deposits (e.g., Donping) along the northern margin of the North China craton (Nie et al., 2004). Even major deposits within the world’s largest orogenic gold province of central Asia, such as Jilau (Cole et al., 2000) and Muruntau (Wall et al., 2004), have been re-interpreted as having intrusion-related origins.

These controversial associations of classification are problematic, but are not surprising, as even key deposits within the TGP are controversial. Hart et al. (2002) suggested that this problem resulted from the inclusion of too many deposit types within a single, complex model and suggested a more-refined intrusion-related gold model that excluded controversial epizonal (e.g., Donlin Creek) and shear-hosted (e.g., Pogo) deposits. Both Pogo and Donlin Creek have been variably considered to be oro-genic (Goldfarb et al., 2000, 2004, 2005; Groves et al., 2003), and intrusion-related deposits (Newberry et al., 1995; McCoy et al., 1997; Ebert et al., 2000; Smith et al., 1999; Thompson and Newberry, 2000; Rhys et al., 2003) and as such highlight the classifi-cation conundrum. The Current Situation

Intrusion-related gold deposits, as currently utilized in the geological literature, refer to an incoherent group of deposits with wide-ranging characteristics, granitoid associations and tectonic settings. Beyond those deposits associated with oxidized por-phyry-copper systems, the most coherent classification is for reduced IRGS. The characteristics of reduced IRGS deposits, as compiled from Lang and Baker (2001), with contributions from Lang et al. (2000) and Thompson and Newberry (2000) are listed below. Emphasis is on well-studied examples from Alaska and Yukon. A plan perspective of the model presented in Figure 2.

1. metaluminous, subalkalic intrusion of intermediate to felsic compositions that lie near the boundary between ilmenite and magnetite series;

2. carbonic hydrothermal fluids; 3. a metal assemblage that variably combines gold with elevated Bi, W, As, Mo, Te, and/or Sb and low concentrations of

base metals;

(Continued from page 5)

Figure 2. General plan model of intrusion-related gold systems from the Tintina Gold Province. Note the wide range of mineralization styles and geochemical variations that vary predictably outward from a central pluton (modified from Hart et al., 2002).

7 October 2005 – Gangue No. 87

4. a low sulphide mineral content, mostly <5 vol%, with a reduced ore mineral assemblage that typically comprises arsenopy-rite, pyrrhotite and pyrite and lacks magnetite or hematite;

5. areally restricted, commonly weak hydrothermal alteration; 6. a tectonic setting well inboard of inferred or recognized convergent plate boundaries; 7. a location in magmatic provinces best or formerly known for tungsten and/or tin deposits

Distinguishing Characteristics of Reduced IRGS

Among those characteristics listed above, the first four are common features associated with orogenic deposits and therein lays the potential for misclassification. Only the final two are potentially diagnostic. Below, other distinguishing characteristics are presented. They are mostly designed to differentiate intrusion-related gold deposits, which are a product of local-scale fluids de-rived from a cooling pluton, from orogenic deposits that are considered to result from crustal-scale fluids derived through meta-morphic dehydration (Groves et al., 1998; Stuwe, 1998). Some features exclusively differentiate reduced IRGS. No single char-acteristic is diagnostic, but a suite of features is most effective to provide evidence of intrusion-related origin. Tectonic Setting

Reduced IRGS deposits are best developed in intrusions that were emplaced into ancient continental margins behind accretion-ary or collisional orogens and subduction-related magmatic arcs. Preferred host strata include reducing basinal miogeoclinal sedi-mentary or metasedimentary rocks. Gold-related intrusions in Yukon are undeformed as they were intruded millions of years after regional deformation. Metal Zoning

Thermal gradients surrounding cooling plutons are steep and result in temperature-dependent concentric metal zones that de-velop outward from pluton margins for distances up to a few kilometres, or just beyond the thermal aureole. Pluton-proximal gold mineralization may be associated with Bi, Te, and W aureole-hosted mineralization will have an As or Sb tenor, and distal miner-alization may be related to Ag-Pb-Zn (Fig. 2). Diverse Deposits

Fluids exsolving from cooling plutons are opportunistic and cool quickly, thus depositing metals in several available geological settings. Resulting mineralization is commonly of several different styles: variably intrusion and country-rock hosted consisting of skarns, replacements, disseminations, stockworks and veins (Fig. 2). Gold mineralization is characterized by a wide range of gold grades, with bulk mineable volumes present at the 0.8 to 1.5 gram per tonne level (e.g., Fort Knox). Sheeted Veins

The most distinctive style of gold mineralization in reduced IRGS are sheeted arrays of parallel, low-sulphide, single-stage quartz veins which are found over 10s to 100s of metres and preferentially located in the pluton’s cupola (Fig. 3). These veins are unlike multidirectional interconnected stockworks characteristic of porphyry systems or antithetic tensional vein arrays typical of


Figure 3. Outcrop scale exposure of A) an array of auriferous sheeted quartz veins in the apex of the pluton at Clear Creek, Yukon. Altera-tion is limited to narrow selvages adjacent to the vein. Marker for scale. B) Sheeted veins at the Fort Knox gold deposit in Alaska, here shown offset slightly by a fracture, are less parallel and slightly more irregular but still do not form multi-directional stockworks, thus distin-guishing this deposit type from porphyry deposits. Alteration is limited to thin selvages adjacent to the veins.

A B


orogenic deposits. Pluton Features

Mineralizing plutons have “smoking gun” characteristics that indicate the likelihood of generation of hydrothermal fluids. Physical features and geochemical support should exist for high volatile contents, fluid exsolution, evidence of rapid fractiona-tion, zoned plutons, porphyry textures, presence of aplite and pegmatite dykes, quartz and tourmaline veins, greisen altera-tion, miarolitic cavities and/or unidirectional-solidification tex-tures, preferably in the plutons’ apices (Fig. 4). Redox State

Reduced IRGS are associated with felsic, ilmenite-series plu-tons that lack magnetite, have low magnetic susceptibilities and aeromagnetic response, and have low ferric:ferrous ratios of <0.3. These types of plutons are uncommon in arc and fore-arc settings where orogenic gold deposits are most common. Timing

Intrusion-related deposits are coeval (± 2 m.y.) with their as-sociated, causative pluton (i.e., Hart et al., 2004b). Conclusions

Beyond the debates and genetic controversies that take place in the geological literature, the main reason for distinguishing between intrusion-related and orogenic gold classifications is the fundamentally different approaches to gold exploration methodology required by each model. Intrusion-related gold classifications are highly varied, mostly poorly constrained and share a large number of associated features with orogenic gold systems. The reduced IRGS model is among the best classified of intrusion-related models and is easily differentiated from other gold deposit classifications for a set of distinguishing char-acteristics that are particular to fluid generation in a cooling plu-ton. Acknowledgements

This work benefits from discussions and contributions from Richard Goldfarb, John Mair, David Groves and my colleagues at the Yukon Geological Survey. Additionally, comments and a review by Lara Lewis is appreciated.

References Agricola, G., 1556. De Re Metallica: Froben Press, Basel; translated

into English by Hoover, Herbert Clark and Lou. Henry Hoover; Mining Magazine, London, 1912; (reprinted by Dover Publica-tions, Inc., New York, 1950).

Bakke, A.A., 1995. The Fort Knox “porphyry” gold deposit - Structurally controlled stockwork and shear quartz vein, sulphide-poor miner-alization hosted by Late Cretaceous pluton, east-central Alaska, in Schroeter, T.A., ed., Porphyry Deposits of Northwestern Cordil-lera of North America. Canadian Institute of Mining and Metallurgy Special Volume 46, p. 795-802.

Bierlein, F.P. & McKnight, S., 2005. Possible intrusion-related gold sys-tems in the Western Lachlan Orogen, southeast Australia. Eco-nomic Geology, v. 100, p. 385-398.

Cole, A., Wilkinson, J.J., Halls, C. & Serenko, T.J., 2000. Geological characteristics, tectonic setting and preliminary interpretations of the Jilau gold-quartz vein deposit, Tajikistan. Mineralium De-posita, v. 35, p. 600-618.

Cox, D.P. & Singer, D.A. (eds.), 1986. Mineral deposit models. U.S. Geological Survey Bulletin 1693, 379 p.

de Ronde, C.E.J., Faure, K., Bray, C.J. & Whitford, D.J., 2000. Round Hill Shear Zone-Hosted Gold Deposit, Macraes Flat, Otago, New Zealand: Evidence of a Magmatic Ore Fluid. Economic Geology, v. 95, p. 1025-1048.

DeLaunay, L., 1900. Les variations de felons métallifères en profondeur. Reviews Géneral de Science, v. 11, p. 575-580.

Ebert, S., Miller, L., Petsel, S., Dodd, S., & Kowalcyk, P., 2000. Geol-ogy, mineralization, and exploration at the Donlin Creek project, southwestern Alaska. The Tintina Gold Belt: Concepts, Explora-tion and Discoveries, British Columbia and Yukon Chamber of Mines, Special Volume 2, p. 99-114.

Emmons, W.H., 1926. Relations of metalliferous lode systems to igne-ous intrusions. Transactions of the American Institute of Mining, Metallurgy and Engineering, v. 74, p. 29-70.

Emmons, W.H., 1933. On the mechanism of the deposition of certain metalliferous lode systems associated with granitic batholiths, in Ore deposits of the western States: New York, American Institute of Mining and Metallurgical Engineers, p. 327–349.

Goldfarb, R.J., Ayuso, R., Miller, M.L., Ebert, S.W., Marsh, E.E., Petsel, S.A., Miller, L.D., Bradley, D., Johnson, C. & McClelland, W., 2004. The Late Cretaceous Donlin Creek deposit, southwestern Alaska—controls on epizonal formation. Economic Geology, v. 99, p. 643-671.

Goldfarb, R.J., Baker, T., Dubé, B., Groves, D.I., Hart, C.J.R. & Gosselin, P., 2005. Distribution, Character, and Genesis of Gold Deposits in Metamorphic Terranes. Society of Economic Geolo-gists, Economic Geology 100th Anniversary Volume.

Goldfarb, R.J., Hart, C.J.R., Miller, M., Miller, L., Farmer, G.L. & Groves, D.I., 2000. The Tintina Gold Belt: A global perspective. British Columbia and Yukon Chamber of Mines, Special Volume 2, p. 5-34.

Groves, D.I., Goldfarb, R.J., Robert, F. & Hart, C.J.R., 2003. Gold de-posits in metamorphic belts: Overview of current understanding, outstanding problems, future research, and exploration signifi-cance. Economic Geology, v. 98, p. 1-29.

Groves, D.I., Goldfarb, R.J., Gebre-Mariam, M., Hagemann, S.G. & Robert, F., 1998. Orogenic gold deposits: A proposed classifica-tion in the context of their crustal distribution and relationships to other deposit types. Ore Geology Reviews, v. 13, p. 7-27.

Hart, C.J.R., McCoy, D., Goldfarb, R.J., Smith, M., Roberts, P., Hulstein, R., Bakke, A.A. & Bundtzen, T.K., 2002. Geology, exploration and discovery in the Tintina gold province, Alaska and Yukon. Society of Economic Geologists Special Publication 9, p. 241-274.

Hart, C.J.R., Goldfarb, R.J., Lewis, L.L & Mair, J.L., 2004a. The North-ern Cordillera Mid-Cretaceous Plutonic Province: Ilmenite/Magnetite-Series Granitoids and Intrusion-Related Mineralisation. A Special Issue of Granites and Metallogeny : The Ishihara Vol-ume, Resource Geology, v. 54, no. 3, p. 253-280.

Hart, C.J.R., Villeneuve, M.E., Mair, J.L., Goldfarb, R.J., Selby, D.,


Figure 4. Vug at Fort Knox pluton filled with coarse-grained quartz, feldspar, and amphibole. Features such as this are indicative of the pluton having reached fluid saturation and having produced a hydro-thermal fluid and typically occur proximal to pegmatitic or aplitic dykes.


Creaser R.A. & Wijns, C., 2004b. Comparative U–Pb, Re–Os and Ar–Ar geochronology of mineralizing plutons in Yukon and Alaska. SEG 2004 Predictive Mineral Discovery Under Cover, Extended Abstract, J. Muhling et al. (eds.), Perth, Australia, p. 347-349.

Hitchins, A.C. & Ossrich, C.N., 1995. The Eagle zone gold-tungsten sheeted vein porphyry deposit and related mineralization, Dublin Gulch, Yukon Territory, in Schroeter, T., ed., Canadian Institute of Mining and Metallurgy, Special Volume 46, p. 803-810.

Hollister, V.F., 1992. On a proposed plutonic porphyry gold deposit model. Non-renewable Resources, v. 1, p. 293-302.

Ishihara, 1981. The granitoid series and mineralization, in Skinner, B., ed., Economic Geology 75th Anniversary Volume, p. 458-484.

Keith, S.B. & Swan, M.M., 1987. Oxidation state of magma series in the southwestern U.S.: Implications of geographic distribution of base, precious and lithophile metal metallogeny. Geological Society of America Abstracts with Programs, v. 19, p. 723-724.

Kontak, D.J., O'Reilly, G.A., MacDonald, M.A., Horne, R.J. & Smith, P.K., 2004. Gold in the Meguma Terrane, southern Nova Scotia. Is there a continuum between mesothermal lode gold and intru-sion-related gold systems? Geological Association of Canada-Mineralogical Association of Canada Joint Annual Meeting, St. Catharines, Ontario, May 2004, Abstracts Volume 29, p. 374.

Lang, J.R. & Baker, T. 2001. Intrusion-related gold systems: the present level of understanding. Mineralium Deposita, v. 36, p. 477-489.

Lang, J.R., Baker, T., Hart, C.J.R. & Mortensen, J.K., 2000. An explora-tion model for intrusion-related gold systems. Society of Economic Geologists Newsletter 40, p.1-15.

Leveille, R.A., Newberry, R.J. & Bull, K.F., 1988. An oxidation state-alkalinity diagram for discriminating some gold-favorable plutons: an empirical and phenomenological approach. Geological Asso-ciation of America Abstracts with Program, v. 20, p. A142.

Lindgren, W., 1933. Mineral Deposits. McGraw Hill, New York and Lon-don, 930 p.

Mair, J.L., 2004. Tectonic setting, magmatism and magmatic-hydrothermal systems at Scheelite Dome, Tombstone Gold Belt, Yukon: Critical constraints on intrusion-related gold-systems. Un-published PhD thesis, The University of Western Australia, Perth, 197 p., plus appendices.

Maloof, T.L., Baker, T. & Thompson, J.F.H., 2001. The Dublin Gulch intrusion-hosted gold deposit, Tombstone plutonic suite, Yukon Territory, Canada. Mineralium Deposita, v. 36, p. 583-593.

Marsh, E.E., Goldfarb, R.J., Hart, C.J.R. & Johnson, C.A., 2003. Geol-ogy and geochemistry of the Clear Creek intrusion-related gold occurrences, Tintina Gold Province, Yukon, Canada. Canadian Journal of Earth Sciences, v. 40, p. 681-699.

McCoy, D., Newberry, R.J., Layer, P., DiMarchi, J.J., Bakke, A., Master-man, J.S. & Minehane, D.L., 1997. Plutonic-related gold deposits of interior Alaska. Economic Geology Monograph 9, p. 191-241.

Miller, J. McL & Wilson, C.J.L., 2004. Stress Controls on Intrusion-Related Gold Lodes: Wonga Gold Mine, Stawell, Western Lachlan Fold Belt, Southeastern Australia. Economic Geology, v. 99, p. 941-963.

Newberry, R. J., McCoy, D.T. & Brew, D.A., 1995. Plutonic-hosted gold ores in Alaska: Igneous vs. metamorphic origins. Resource Geol-ogy Special Issue 18, p. 57-100.

Nie, F.J., Jiang, S.H. & Liu, Y., 2004. Intrusion-related gold deposits of North China Craton, People’s Republic of China. A Special Issue of Granites and Metallogeny : The Ishihara Volume, Resource Geology, v. 54, p. 299-324.

Niggli, P., 1929. Ore deposits of magmatic origin. Thomas Murby and Co., London, England.

Rhys, D., DiMarchi, J., Smith M., Friesen, R. & Rombach, C., 2003. Structural setting, style and timing of vein-hosted gold mineraliza-tion at the Pogo deposit, east central Alaska. Mineralium De-posita, v. 38, p. 863-875

Robert, F., 2001. Syenite-associated disseminated gold deposits in the Abitibi greenstone belt, Canada. Mineralium Deposita, v. 36, p. 503-516.

Roberts, R.G., & Sheahan, P.A., 1988 (eds). Ore Deposit Models. Geo-science Canada, Reprint Series 3, Geological Association of Can-ada, 194 p.

Roberts, R.G. & Sheahan, P.A., 1994 (eds). Ore Deposit Models II. Geoscience Canada, Reprint Series 6, Geological Association of Canada, 194 p.

Rowins, S.M., 2000. Reduced porphyry copper-gold deposits: A new variation on an old theme. Geology, v. 28, p. 491-494.

Rombach, C.S. & Newberry, R.J., 2001. Genesis and mineralization of the Shotgun deposit, southwestern Alaska. Mineralium Deposita, v. 36, p. 607-621.

Schroeter, T.G., 1995 (ed.). Porphyry Deposits of the Northwestern Cordillera of North America. Canadian Institute of Mining and Metallurgy, Special Volume 46, 888 p.

Sillitoe, R.H., 1979. Some thoughts on gold-rich porphyry copper de-posits. Mineralium Deposita, v. 14, p. 161-174.

Sillitoe, R.H., 1991. Intrusion-related gold deposits, in Foster, R.P. (ed.), Gold Metallogeny and Exploration, Blackie, Glasgow, p. 165-209.

Sillitoe, R.H., 1995. Gold-rich porphyry copper deposits: Geological model and exploration implications, in Kirkham, R.V, Sinclair, W.D., Thorpe, R.I., & Duke, J.M. (eds.), Mineral Deposit Modeling, Geological Association of Canada, Special Paper 40, p. 465- 478.

Sillitoe, R.H. & Thompson, J.F.H., 1998. Intrusion-related vein gold de-posits: types, tectono-magmatic settings and difficulties of distinc-tion from orogenic gold deposits. Resource Geology, v. 48, p. 237-250.

Skinner, B.J. (ed.), 1981. Economic geology seventy-fifth anniversary volume. The Economic Geology Publishing Company, Lancaster, Pa., 964 p.

Smith, M.T., Thompson, J.F.H., Bressler, J., Layer, P., Mortensen, J.K., Abe, I. & Takaoka, H., 1999. Geology of the Liese Zone, Pogo property, east-central Alaska. Society of Economic Geologists Newsletter 38:1, p. 12-21.

Spurr, J.E., 1923. The Ore Magmas: A Series of Essays on Ore Deposi-tion. McGraw-Hill, New York, 915 p.

Stuwe, K., 1998. Tectonic constraints on the timing relationships of metamorphism, fluid production and gold-bearing quartz vein emplacement. Ore Geology Reviews v. 13, p. 219-228.

Thompson, J.F.H. & Newberry, R.J., 2000. Gold deposits related to reduced granitic intrusions. Reviews in Economic Geology, v. 13, p. 377-400.

Thompson, J.F.H, Sillitoe, R.H., Baker, T., Lang, J.R. & Mortensen, J.K., 1999. Intrusion-related gold deposits associated with tungsten-tin provinces. Mineralium Deposita, v. 34, p. 197-217.

Tucker, T.L. & Smith, M.T. (chairs), 2000. The Tintina Gold Belt: Con-cepts, exploration and discoveries. British Columbia Chamber of Mines, Special Volume 2, 225 p.

Wall, V.J., 1999. Pluton-related (thermal Aureole) gold. Short Course Notes, Yukon Geoscience Forum.

Wall, V.J., Graupner, T., Yantsen, V., Seltmann, R. & Hall, G.C., 2004. Muruntau, Uzbekistan: a giant thermal aureole gold (TAG) sys-tem, in Muhling, J., Goldfarb, R.J., Vielreicher, N., Bierlein, F.P., Stumpfl, E.F., Groves, D.I., & Kenworthy, S. (eds.), SEG 2004: Predictive Mineral Discovery Under Cover; Extended Abstracts, Centre for Global Metallogeny, The University of Western Austra-lia, Publication no. 33, p. 199-203.

Wall, V.J. & Taylor, J.R., 1990. Granite emplacement and temporally related gold mineralization. Geological Society of Australia, Ab-stract Series 25, p. 264-265.

Walshe, J.L., Neumayr, P. & Cooke, D.R., 2005. Two boxes we don’t need—orogenic and intrusion-related gold systems, in Hancock, H. et al. (eds.), STOMP 2005, ERGU Contribution 64, p. 143.

Wang, L.G., Qiu, Y.M., McNaughton, N.J., Groves, D.I., Luo, Z.K., Huang, J.Z., Miao, L.C. & Liu, Y.K., 1998. Constraints on crustal evolution and gold metallogeny in the Northwestern Jiaodong Peninsula, China, from SHRIMP U-Pb zircon studies of granitoids. Ore Geology Reviews, v. 13, p. 275-292.

Editor’s Note: This article is a synopsis of the Boldy award winning pa-per given at the 2005 GAC-MAC Annual Meeting in Halifax, NS


AWARD WINNERS Congratulations to the 2006 MDD Award Winners!

DUNCAN DERRY AWARD: HOWARD POULSEN, GEOLOGICAL CONSULTANT WILLIAM HARVEY GROSS AWARD: STEPHEN PIERCEY, LAURENTIAN UNIVERSITY These prestigious awards are granted annually by the MDD of GAC and will be presented to the winners at

the MDD luncheon to be held at the Annual General Meeting in Montreal (May 2006).


Exploration and Mining GeologyExploration and Mining Geology CIM’s quarterly journalCIM’s quarterly journal

Volume 13 (2004) of EMG is now available. Future vol-umes will include special volumes on mineral deposits of the Bathurst Mining Camp, pegmatites, and Proterozoic gold deposits.

Volumes 11, 12, and 13 are available to members of MDD at a special affiliated rate of $CDN 75/ $US 55. To pur-chase these volumes, contact Jo-Anne Watier at CIM (Tel.: 514-939-2710 ext 1311; email: [email protected]).

SPECIAL ISSUE: MINERAL DEPOSITS OF NUNAVUTSPECIAL ISSUE: MINERAL DEPOSITS OF NUNAVUTSPECIAL ISSUE: MINERAL DEPOSITS OF NUNAVUT Volume 13, Nos. 1-4, January – October 2004 Table of Contents

An Update on the Geology of the Lupin Gold Mine, Nunavut, Canada P.A. Geusebroek and N.A. Duke

An Overview of the ULU Gold Deposit, High Lake Volcanic Belt, Nunavut, Canada E. Flood, P. Kleespies, M. Tansey, H. Muntanion, and R. Carpenter

Geology of the Izok Massive Sulfide Deposit, Nunavut Territory, Canada I.R. Morrison

The Geology and Mineralization of the High Lake Volcanic-hosted Massive Sulfide Deposit, Nunavut C.A. Petch

Geological Setting of the West Meliadine Gold Deposits, Western Churchill Province, Nunavut, Canada R.L. Carpenter and N.A. Duke

Geological Setting of the Meadowbank Gold Deposits, Woodburn Lake Group, Nunavut R. Sherlock, S. Pehrsson, A.V. Logan, R.B. Hrabi, and W.J. Davis

The Setting and Age of the Bermuda Zn-Pb Showing, Grinnell Peninsula, Devon Island: Implications for MVT Mineralization in the Canadian Arctic I. Mitchell, R.L. Linnen, and R.A. Creaser

Nanisivik Mine―A Profitability Comparison of Actual Mining to the Expectations of the Feasibility Study N.R. Burns and M. Doggett REGULAR PAPERS

Conjugate Oblique-Extension Veins in Shear and Tensile Fracture Systems at the Komis Gold Mine and Muf-feraw Gold Prospect, Northern Saskatchewan B. Lafrance

Get: A Function for Preferential Site Selection of Additional Borehole Drilling A.A. Hassanipak and M. Sharafodin


AN OPINION IN PRAISE OF ACTION Various initiatives are underway and being planned to re-vitalize “The North” through geoscience

Damien J. Duff, P.Geo

CIM Geological Society President

Canada’s commodity-based economy has always relied on “The North” as a supplier of base and precious metals to meet global demand. To this end, established mining camps in northwestern Québec, northeastern Ontario, and the NWT, to name just a few, have sustained production at a world-class scale throughout their histories. The Tim-mins Camp alone is now approaching its 65th million ounce of gold production, while the storied Kidd Creek Cu-Zn operation proudly recorded its 130 millionth tonne of ore milled in 2005.

The problem is, however, that a number of factors are in play across our industry that place continued production at current rates in all our jurisdictions in jeopardy.

Increasing energy costs, human resource shortages, capital item purchase delays among others, immediately come to mind as important risks, no question. Less evident to some people, however, may be the risk posed by re-serve depletion, particularly in our base metal sector but also in our precious metal mines. Our mines are being de-pleted at a higher rate than they can replace reserves (Table 1). Further, these existing reserves are saddled by ad-ditional challenges, most notably those associated with their increasing mining depth and tough economics. To com-pound matters, new mines are not being found at a sufficient rate to keep pace. Statistics show that the rate of new discoveries in Canada has dropped significantly in the period 1997-2004 (Figure 1).

Faced with these difficulties, I’m glad to report that the Canadian mining industry is not sitting on its hands. Who would have expected it to really? You don’t become best in the world at anything by being paralyzed with fear when the chips are down. Goldcorp in Red Lake, Falconbridge in Timmins, and Inco in Sudbury, to name but a few, can all cite examples of how conditions have forced them to do the “undo-able” (particularly in the field of deep mining) in order to secure the future of some of their best operations.

But, interestingly, the public sector is helping too. Initiatives at the municipal, provincial and federal levels are all being undertaken, or are in the advanced planning stages, to help address the problem of reserve depletion and the need for geoscience database enhancement. They have largely been focused in established mining camps, or areas to which I would refer as the near north.

Some of the most exciting amongst these many initiatives with which I have some experience are: the Discover Abitibi and Lake Nipigon Geoscience Initiatives in Ontario. Both are a product of an unprecedented level of coopera-tion among the public and private sectors. In excess of $16 million has been raised to complete a huge number of high value regional surveys in the fabled Timmins-Kirkland Lake corridor as well as the highly prospective geological terrains around Lake Nipigon in northwestern Ontario. The amount of company interest in the results has been sig-nificant and, already, diamond discoveries are being directly attributed to results of the former initiative. The amount of support likewise at the municipal level for these projects has been phenomenal.

On other fronts as well, the Ontario and federal governments have similarly been pulling their weight. In 2005, the Ontario Budget announced a funding commitment of $15M over three years for geological mapping in the Far North

Commodity 1988-2003

How many

Years left?

Copper -51% 10.5

Nickel -31% 21

Lead -89% 5.5

Zinc -70% 7

Silver -65% 7

Gold -42% 15

Table 1. Mineral Reserve Levels in Canada (Source: MAC)

Figure 1. New Discoveries in Canada (1997-2004); source PDAC.


(Figure 2). This area has been generally ne-glected by all sectors, but new discoveries clearly indicate that the area has immense future mineral potential. For example, De Beers Canada is on track to open a diamond mine 90 km west of Attiwapiskat in 2008, which, when in production, will permanently employ 400 people. As well, some truly phe-nomenal base metal results are being re-ported in the same general area by Spider Resources and KWG.

My personal view is that The North in all regions of Canada is still a cornerstone for us as an industry. And whereas it is fair to say that our existing camps are becoming more mature, with thus perhaps a lesser chance of significant new exploration success, else-where in The North-particularly north of 50˚- with its huge area of untapped potential, represents the next frontier. But how do we best take advantage of the obvious opportuni-ties it presents?

First, we take all necessary steps to docu-ment and understand the geology of The North so that we can optimize our chances of economic success. Of necessity, govern-ments must take the lead on this. Where they go, industry will follow.

Second, at the municipal level at least, we must start thinking of these more remote re-gions as extensions or even “catchment ar-

eas” around our established mining communities. By this I mean that these communities may have to begin recog-nizing that decisions made at the higher levels to devote funds and other resources to The North in fact benefit them as well. As an example, the current building boom in Timmins is based in part on the economic spin-offs of the Victor Mine project some 500 km to the north. By helping others in The North, existing mining communities can help them-selves.

Third, other new opportunities in The North are enhanced by a complimentary infrastructure development plan. Power, roads, and ports are just a few examples of the infrastructure elements, which if available in the North, change everything. The Ontario Mining Association, in its comments to the Ontario Government on the New Mineral Development Strategy for Ontario discussion paper states: “[the strategy] needs to be part of an overall industrial strategy for Ontario, which includes as a component an energy policy and infrastructure enhancement and develop-ment (plan) in the Far North”.

This is all great stuff admittedly but we geoscientists are really into improving our geoscience data collection every-where, right?

Well, here’s the really exciting thing. With the support of the National Geological Surveys Committee (or NGSC for short), and the support of all of Canada’s Mines Ministers, Natural Resources Canada has launched a two year pro-ject called Cooperative Geological Mapping Strategies across Canada “to formulate and communicate the federal component of a 10-year implementation plan for CGMS”. This will be, when finally approved, a multi-million dollar commitment (possibly up to $500m over 10 years!) to geoscience. The main strategic goal is: “contributing to new resource-based regional economic development opportunities in frontier areas and the North”. In Ontario at least, this represents a huge opportunity to compliment the Far North Initiative. Kudos all the way around on this one!

At the same time, Targeted Geoscience Initiative #3 (TGI-3) is in the planning stages (a MegaTEM survey is al-ready being flown in Québec). This is another federal government-funded initiative “with a focus on base metal re-serves in established mining communities” across Canada. The provinces are undertaking their own initiatives in concert with the federal government (the OGS has come out of the gate fast as has, I understand, the Ministére in


Figure 2. Far North Mapping Initiative Location. Source: OGS


Québec. I’d be very surprised if other provinces, Manitoba for example, were not also chomping at the bit to attempt to compliment this effort in their respective jurisdictions, and expected total funding levels are $25 million over five years. Technical review sessions have already been held in various locations to discuss possible projects and, pending final budget clearance at the federal level, further work in earnest should commence soon.

So, what can we infer from all of these positive developments? Well, the planets seem to be lining up finally (did I also mention that 61% of Canadians, in a poll recently commissioned by the Mining Association of Canada, stated that “the mining industry makes a positive contribution”?!). All the players with an interest in ensuring Canada re-mains at the forefront of the pack of preferred mining and exploration jurisdictions around the globe are planning and working diligently together. They are addressing geoscience data shortages and other de-enablers to development.

As geoscientists with a vested interest in mineral deposits in this country, we all should be adding our voices of support to all levels of government while at the same time ensuring that we convince the powers that be at our re-spective workplaces of the benefits associated with all of these (and other) initiatives.

Our great country and industry were opened up by pioneers and risk takers. Let’s now carry on in this proud tradi-tion by using 21st century tools in conjunction with a 21st century cooperative spirit and attitude. The challenges to success in The North will always be significant. We need to lay the groundwork now, however, to help overcome them. Through collaboration we all stand a better than reasonable chance of success.

Let’s also look for ways to both attract youth to our industry, and nurture and support students of the earth sci-ences. And finally, let’s be sure to continue to work together to open up The North and help ensure a bright future for generations present and future!


15 October 2005– Gangue No. 87 15 October 2005– Gangue No. 87

The following Symposia are sponsored by the Mineral Deposits Division of the Geological Associa-tion of Canada: SM-2 Diversification of mineral exploration Michel Jébrak (UQAM), Michel Malo (INRS) Contact: [email protected] Sponsored by : Mineral Deposits Division and Divex Description: During the final 20 years of the 20th Century, mineral exploration in Canada, and specifically in Abitibi (Quebec and On-

tario), was oriented towards discovering new gold deposits. Meanwhile, production of base metals declined. At the turn of the cen-tury, investment in exploration and the rate of new discoveries were also very low. In order to stay competitive, the mineral indus-try must diversify its exploration strategies and needs new metallogenic models, new tools and new technology. Finding new mines in Canada, including in the little-explored northern latitudes, is more than ever a challenge for the industry. The symposium seeks contributions from researchers in economic geology under the four sub-themes listed below, with the aim to contribute to the diver-sification of mineral exploration. SM-2A Hydrothermal ore deposits in high-grade metamorphic environments Patrice Roy (MRNFQ), Louise Corriveau (CGC-Québec) SM-2B Sedimentary rock hosted mineral deposits Georges Beaudoin (Université Laval) SM-2C Ore deposits in brecciated rocks (Iron oxide, uranium, porphyry) Michel Jébrak (UQAM) SM-2D New tools and new technologies for min-eral exploration Michel Chouteau (École Polytechnique)

SM-2A Hydrothermal ore deposits in high-grade metamorphic environments Patrice Roy (MRNFQ), Louise Corriveau (CGC-Québec) Contact: [email protected]

SM-2B Sedimentary rock hosted mineral deposits Georges Beaudoin (Université Laval) Contact: [email protected]

SM-2C Ore deposits in brecciated rocks (Iron oxide, uranium, porphyry) Michel Jébrak (UQAM) Contact: [email protected]

SM-2D New tools and new technologies for mineral exploration Michel Chouteau (École Polytechnique) Contact: [email protected]

SM-3 Precambrian evolution and mineral deposits of the Canadian and Brazilian shields: similarities and differences Nuno Machado (GEOTOP-UQAM), Gema Olivo (Queen's U.) Contact: [email protected] Sponsored by : Mineral Deposits Division; CAMECO Corporation

FOR MORE INFORMATION ON THE GAC-MAC CONFERENCE, VISIT THE WEBSITE : WWW.ER.UQAM.CA/NOBEL/GACMAC/WELCOME.HTML


CIM GEOSOC Delivering Satisfaction through Quality

Check out one of the premier geological programs anywhere.

It takes place over 3 days in May 2006 in downtown Vancou-

ver. Eight technical sessions are being planned covering:

IOCG, Diamonds, Porphyry, Archaean Gold, Uranium, SEDEX ,

VMS and world-class Nickel deposits. These will be compli-

mented by two (2-day) post-conference fieldtrips.

Be sure to attend!

Highlights

• Eight ore deposit-type tech-nical sessions

• Two (2-day) post conference field trips in British Columbia

• Student Poster Session

• Fabulous networking oppor-tunity

• World-Class Exhibition

Contact person: [email protected] General Contact: [email protected]

GEOSOC PULLS TOGETHER WORLD-CLASS PROGRAM AT 2006 CIM CONVENTION

May 14-16th Vancouver Convention Centre

17 October 2005– Gangue No. 87 17 October 2005– Gangue No. 87

BOOK REVIEWBOOK REVIEW INCO COMES TO LABRADOR Author: Raymond Goldie Published by: Flanker Press Ltd., St. John’s, NL, 2005 Reviewed by: Peter M. Dimmell, P.Geo., St. John’s, NL “Inco Comes to Labrador” is another in a long line of books, which describe the dis-covery and subsequent development of some of the major deposits (and supposed deposits) that have been found over the past twenty to thirty years. Many of these books are written by reporters who covered the stories as they developed such as the Busang “gold deposit” of BreX, the diamond discoveries in the Northwest Terri-tories, or Voisey’s Bay, the subject of this book. Ray Goldie, the author of “Inco Comes to Labrador”, is a geologist and a mining analyst with project evaluation training. He therefore brings a different approach and view to the subject that is more related to the movement of share prices and the trials and tribulations of the takeover and development process than other authors who have written on the sub-ject. The book also highlights two of the most important aspects of exploration – geological mapping and the work of prospectors.

The book starts with a short history of the author, from his education in New Zealand, to his subsequent move to Can-ada, his work experience, first as a bush geologist with Kennco and others, and then with various “mining houses” as a mining analyst on Bay Street in Toronto. He describes how he learned to value properties and the valuation of pro-jects/companies, tongue in cheek, as being a “simple process”. He then describes how it is done by estimating the net present value of various parts of the companies / projects, assuming certain prices and milestones – anything but simple and dependent upon timing. Early nickel/copper/PGE exploration in Labrador by Kennco in the 1970’s, which the author was part of, is described, first in the Kiglaplaits and then in the Harp Lake intrusion where “colour anomalies” (gossans), located by helicopter were followed up, resulting in the discovery of a number of sulphide occurrences, most carrying minor nickel-copper mineralization. This part of the book was interesting to me as I had evaluated much of the assessment work in Lab-rador as a project geologist for Noranda. I had looked at the Kennco work in the Harp Lake intrusion and had been impressed by the helicopter mapping of the gossans as a simple but expedient way of quickly evaluating areas where there is little tree cover. Goldie also recognized the value of the early mapping work done by geologists Bruce Ryan and Dan Lee who first mapped the Nain Plutonic Suite (NPS) and actually discovered and described the gossan on Discovery Hill, by dedicating the book to them. This gossan, when sampled by Al Chislett and Chris Verbiski in 1993, resulted in the discovery of the Voisey’s Bay deposit. The book provides a good study of stock prices related to various phases of the exploration/acquisition/negotiation process and shows how native/indigenous peoples can delay development unless they are brought into the process early on. He also shows how politics, especially economic nationalism, can affect the development of a deposit and how “expectations” can be raised by promoters such as Robert Friedland, who wanted to get the most for the deposit and politicians such as Clyde Wells and Brian Tobin, who used the discovery to improve their position at the polls and in Tobin’s case, to get himself elected for a second term. The history of the processing part of the project through a smelter/refinery, first promised by Inco, then rescinded, then replaced by the Hydromet process pilot plant, and planned commercial plant, is described and put in the global context of nickel supply and demand. I didn’t particularly like the conversational style of the book whereby the author talks to composite characters, such as Patricia, about the stock price, timing of announcements, etc., feeling that it might have detracted from the story. Also my recollections of various aspects of the discovery and development of Voisey’s Bay, living in Newfoundland and Labrador and being part of the Voisey’s Bay staking rush and subsequent exploration, are sometimes slightly at odds to the author’s. That said, the book is a good summary of the ups and downs related to the development of one of the major nickel-copper deposits in the world today and most likely a new “camp” of deposits, where discover-ies will be made for the next 50 plus years. I recommend the book to anyone who wants to look beyond the rhetoric of the politicians and promoters, you will get a better insight into the process of development of a deposit and the pit-falls along the way.

MEETINGS, WORKSHOPS, & FIELDTRIPSMEETINGS, WORKSHOPS, & FIELDTRIPSMEETINGS, WORKSHOPS, & FIELDTRIPS

2006 • March 5-8 - PDAC 2006 International Convention, Metro Toronto Convention Centre, Toronto, Ontario;

http://www.pdac/conv/index.html • April 2-16 - Modular Course in Exploration for Magmatic Ore Deposits, Mineral Exploration Research Centre, Department of

Earth Sciences, Laurentian University, Sudbury, Ontario; http://earthsciences.laurentian.ca; contact: [email protected] • May 14-17 - GAC/MAC Annual Meeting 2006, Université du Québec, Montreal, Québec; http://www.gacmac2006.ca • May 14-17- Canadian Institute of Mining, Metallurgy, and Petroleum Conference and Exhibition 2006, Vancouver Convention

Center, Vancouver, BC; http://www.cim.org/vancouver2006/ • May 17-21 - Geofluids V, University of Windsor, Windsor, Ontario; http://www.geofluids5.org • August 21-24 - 12th Quadrennial IAGOD Symposium, “Understanding the Genesis of Ore Deposits - to meet the Demands of the

21st Century,” Moscow, Russia; http://www.iagod.sgm.ru/; contact: [email protected] • October 22-25 - Geological Society of America Annual Conference, Philadelphia, PA; http://www.geosociety.org/meetings • September 10-12 - CIM Geological Society Field Conference; Uranium: Athabasca Deposits and Analogues, Saskatoon, SK;

http://www.saskuranium2006.ca

2007 • January 29-February 1 - Mineral Exploration Roundup 2007, The Westin Bayshore, Vancouver, BC;

http://www.amebc.ca/roundupoverview.htm; contact: [email protected] • March 4-7 - PDAC 2007 International Convention, Metro Toronto Convention Centre, Toronto, Ontario;

http://www.pdac/conv/index.html • May 23-25 - GAC/MAC Annual Meeting 2007, Yellowknife, NWT; http://www.nwtgeoscience.ca/gac_mac • August 20-24 - 9th Biennial SGA Meeting, Dublin, Ireland; http://www.e-sga.org/sga.html • September 24-30 - Ores and orogenesis: Circum-Pacific Tectonics, Geological Evolution, and Ore Deposits, Tucson, Arizona;

http://www.agssymposium.org/


Information for Contributors: The Gangue began as a quarterly publication assembled by the Mineral Deposits Division of GAC, which was distributed to its members in hard copy form. In 2005, MDD and the Geological Society of CIM decided to join forces and jointly publish the Gangue. The Gangue is currently distributed to members of MDD and CIM-GeolSoc as an online publication. The Mineral Deposits Division of the Geological Association of Canada is Canada’s foremost society for promoting the study of mineral deposits by supporting local and national meetings, symposia, short courses and field trips. We sponsor the publication of re-search relating to ore deposits and metallogeny, and recognize the contributions of outstanding Canadian economic geologists by annually awarding the Duncan Derry and William Harvey Gross medals and the Julian Boldy Certificate.

Publication Schedule: SUBMISSION DATE December 15 January March 15 April June 15 July September 15 October

The objective of this newsletter is primarily to provide a forum for MDD and CIM-Geological Society members and other profes-sionals to voice new ideas, describe interesting mineral occur-rences or expound on deposit models. Articles on ore deposits, deposit models, news events, field trips, book reviews, confer-ences, reprints of presentations to companies, mining groups or conferences, or other material which may be of interest to the economic geology community are welcome. Manuscripts should be submitted by email in WP or WORD format. A printed version should be mailed or FAXed. Illustrations should be camera-ready (ideally as CDR digital files); photos should be of good quality. Short items dealing with news events or meetings can be sub-mitted by FAX, postal mail or email. Contributions may be edited for clarity or brevity.

For Information & Submissions:

Kay Thorne—THE GANGUE NB DNR-Minerals PO Box 6000, Room 150 Fredericton, NB E3B 5H1 Email: [email protected] Tel: (506) 453-2206 Fax: (506) 453-3671

Intrusive Related Gold Deposits

Documents

Transcript of Intrusive Related Gold Deposits